Science Simple Machines

Explain the purpose or function of simple machines

- To transform energy - Transfer forces from one location to another - Change direction of a force - Change magnitude of a force - Increase/decrease speed

Describe the first class lever and its resultant MA

1st class lever: - Fulcrum between effort force and load - Used for power or precision - Exerts a force on the load greater than the force you exerted on the lever - Magnifies force of changes direction MA = >1

Describe the second class lever and its resultant MA

2nd class lever: - Load between effort force and fulcrum - Used to exert a greater force on the load than the effort force exerted on the lever - Magnifies force MA = >1

Describe the third class lever and its resultant MA

3rd class lever: - Effort force between fulcrum and load - Used to move a load quickly (speed) Must exert a greater force on the lever than the lever exerts on the load, but in exchange the lever moves the load a greater distance - Magnifies distance and speed MA = <1

Simple machines can yield mechanical advantages greater than 1, equal to 1 or less than 1; Distinguish between each advantage and explain what the point of each is

>1: Less input force; ore output force (i.e opening a paint can) This is used to multiply the input force acting on an object =1: The input force is equal to the output force (i.e raising a blind). This is used to change the direction of the output force. <1: More input force; less output force (i.e hitting a baseball) This is used to increase the distance over which the force is applied or the speed

Define system

A combination of interdependent parts that form a unified whole

Define force

A push/pull that acts on an object

Describe the difference between contact and at-a-distance forces

Contact: Must touch objects they push/pull (i.e hockey stick and puck) At-a-distance: Push/pull objects without touching them (i.e magnets)

Define fulcrum

Fixed point that supports the lever

Define load

Force of object moved by lever

Explain how friction affects the input force and ultimately the mechanical advantage of simple machines

Friction is the resistance that one surface encounters when moving over another. The MA will be less when considering friction because additional force would be required to overcome the force of friction, which means that the input force would be larger, resulting in a smaller MA

Define the term ideal mechanical advantage and express it as a mathematical formula

IMA: The mechanical advantage of a machine that has no friction IMA = Input distance/Output distance or Din/Dout

Define effort arm

The distance from the effort force to the fulcrum

Define load arm

The distance from the load to the fulcrum

State the 6 types of simple machines discussed in this unit

Screw, Wedge, Wheel and axle, Pulley, Lever, Inclined plane

Define effort

Input force you exert on a lever to make it move

Define the terms "input force" and "output force" as they apply to simple machines

Input force: Amount of force you exert on a machine Output force: the amount of force the machine exerts on an object in result of the input force

Identify and classify simple machines in everyday phenomena

Lever: Seesaw Inclined plane: Ramp Wedge: Axe Pulley: Flagpole Wheel and Axle: Doorknob Screw: Bottle cap

Describe how to calculate mechanical advantage or ideal mechanical advantage in a lever

MA = Fout/Fin or MA = Length of input arm/Length of output arm IMA= Din/Dout

Describe how to calculate mechanical advantage or ideal mechanical advantage in an inclined plane

MA = Length of slope/Height of slope IMA = Length of incline/height of incline

Describe how to calculate mechanical advantage or ideal mechanical advantage in a wheel and axle

MA = Radius of wheel/Radius of axle IMA = Radius of axle/Radius of wheel

Describe how to calculate mechanical advantage or ideal mechanical advantage in a pulley

MA = Win/Wout IMA = # of strands of rope directly supporting load

Define the term mechanical advantage and express it as a mathematical formula

MA: The amount by which a machine can multiply an input force is called its mechanical advantage. MA = Fout/Fin

Distinguish between mass and weight

Mass: Amount of matter in an object Weight: Amount of gravitational pull on an object

Distinguish between the terms single fixed pulley and movable pulley

Single fixed pulley: Pulley does not multiply input force, but does change direction of force from up to down (i.e blinds) Movable pulley: Changes direction of force, multiplies force too

Describe the principle of the machine

Overall, the amount of work doesn't change

Describe the differences between potential and kinetic energy

Potential: Energy that is stored (elastic energy) Kinetic: Energy of objects in motion (thermal energy)

Define energy

The ability to do work (Joules)

Define the term work and express it as a mathematical formula

Work: the amount of effort spent when force is applied to an object and the object moves. Work is only done when a force causes movement. Work = Force (N) x Distance (m) or W = Fd